System for protecting electric-current-distributing nets against temporary interruptions



M. HIICHSIADTER.

SYSTEM FOR PROTECTING ELECTRIC CURRENT DISTRIBUTING NETS AGAINST TEMPORARY INT ERRUPTIONS. APPLICATION FILED OCT. 20, I9I4.

1,404,437.. Patented Jan. 24,1922.

77w. 7&2. 77 w. 77 w.

W'FZ-neSsGS InvenFOV': W WW Maw v W*W %ZQ UNITED. STATES PATENT I OFFICE.

MARTIN 'HocHsTliDTER, or BERLIN, GERMANY, assren'oa TO N. v. LYN-PROTECTIE,

MAATSCHAPPIJ TOT EXPLOITATIE VAN ELECTRO-TECHNISCHE EN ANDERE TBOOIEN, OF THE HAGUE, NETHERLANDS, A DUTCH CORPORATION.

SYSTEM FOR PROTECTING ELECTRIC-CURRENT-DISTRIBUTING NETS AGAINST TEMPORARY INTERRUPTIONS.

Specification of Letters Patent. Patented an. 24, 1922 Application filed October 20, 1914. Serial No. 867,684.

I (GRANTED UNDER THE PROVISIONS OF THE ACT OF MARCH 3,;I921, 41 STAT. L., 1813.) i

the system only the defective portion when its insulation is mechanically or electrically affected. A primary object of the invention is to operate the controlling system even during the formation period of leakages and breakdowns and in the case of undue overtension (excess voltage) thereby or otherwise locally produced, i. e. providing a general safety means to protect electric networks section by section against all' kinds of disturbances originating within such systems or networks and thus rendering electric power transmission safer than heretofore.

The arrangement according to my inventron involves the addition of a special conductor, specially connected and arranged in relation to the respective main, which special conductor will hereinafter be called, control conductor. v

In ordinary working condition a well defined state of electric equilibrium is kept up between each main and its respective control conductor by way of which releasing devices or operating devices interpolated 1n the c'ontrol sections keep the section switches switched in. However, in the event of a leakage, breakdown, or other defect, the relative electric state of equilibrium mentioned above between each two coordinated and cooperating conductors will be disturbed.

Now, it isa prominent feature of my invention in order to safely and simply bring about the above said conditions to provide ful current or be free fromit. While prethe control conductor as a said one or morecontrol conductors in proximity to the respective metallic main to be controlled, either within the main part of its electric field or imbedded in its metallic interior. The control conductor or conductors when connected to the main at both ends of a section and when imbedded into. the metallic core of the main may form art of its copper strands lightly insulated rom the rest and thus may either be carrying useferred forms of systems of connections embodying this invention are illustrated upon the accompanying sheet of drawings, yet it is to be understood that minor detail changes may be made without departing from the scope thereof.

current flowingjthrouh the controlcon ductor neutralized within the relay.

Fig. 9, is a modification of Fig. 5. V Fig-10, is a control system with a plurality of control conductors foreach main conductor.

Figs. 5, 6, 9, and 10, each represent aline section each end of which is a distributing or branching point, which points may also consist of a transformer station or a sub station. Any desired number of such sections may be assumed as connected in series or parallel or in ring lines to build up the electric network.

FigsQl, 2, and 3, indicate how-to preferably build up the main conductor (1) and control conductor (2) both forming one (3). This arrangement 'of strandedponductors alsostrengthens and simplifies the construction to such an extent that practi cally no complicationsandno appreciable enhancement of price is brought about compared with an. ordinary copper cable.. Be-

sidesthisthe control conductor. according; 'to the diagrams Figs. 5 to 10, is to be coning devices (8) having their primary coils nected to its main at the terminals of each section, thus, especially when used for carrying useful current the control conductor will form part of the main not only in a mechanical butal'so in an electrical sense. These diagrams do not illustrate the structure of the 'conductors-,'but it will be understood that any suitable conductor structure nay he adopted for the circuit arrangementsshown in these diagrams, for instance any one of I the cable structures illustrated by Figs. 1

' to 4511133 be employed.

Fig. 1, shows the control conductor in flat form occupying only partofthe surface of the main, whereas in Fig. 2, the control con- Qductor fully surrounds concentrically its '7 main. conductor. According to Fig. 8, the

weakly insulated control conductor may be arranged anywhere in the interior of the mainlconducton In Fig. 4E the'main conductor comprises a core (1) and a sleeve or mantle (1).

The purpose of the subdividing of the main core into a core 1 and a'mantle (1) insulated therefrom I is to free" the core. (whicha-carries a considerable part of the useful current) from 'all charging current which flows into the section on account of its-electrostatic capacity. 7 If therefore, as

"more fully explained below, a control system including the control conductor (2) is governed bythe core-conductor, i. e. by way of the inductive coil 12 (Fig. 4:) the influence 7 of the normal chargin' currents of the sec- "tion can be exclude system. l j r r Figs. 5 to 10 show diagrams for only one main conductorof multi-conductor or poly.- phase network, the; control system for each one being perfectly independent of, and equal to theothers. -The arrows with a dot or circle at.their back end-indicate electric" currents, the feathered ones indicate. mag- 'vrnetic fields; thearrows shown in full lines indicate currents andfieldsin the normal working condition of the system. and the arrows shown in dotted lines indicate currents and fields as they result from a defective condition of the system.

, In Fig. 5, the main conductor controlled is provided with the control con- 'ductor '(2) the insulation (3) of which is 'not shownin Figs. 5 to 10 of the drawing, 7 it being understood, as stated above, that the detail construction of main conductor, con- .proportion to the main current regarding from the control (1) a be differential relays, actuate the switches f1 and 41 in any well known or 'approved manner (not shown). The control conductor (2) is connected at 6 to the main conductor at each section end. Transformer stations (7) are thedistributing points in this case. At each section end there are voltage changincluded in the main conductor 1 and their secondary coils-in the control conductor 2. These devices combine to a certain extent, featuresof current transformers and booster transformers, they supply, in relation to the main current, anadditionaltension into the control conductor without disturbing appreciably the conditions of the main circuit. These transformers, therefore,together withs5 the ratio of resistancesdefine the ratio of the main current to' the control current. The secondary windings of the transformers (8) may -be connected as well in series as in opposition, in the same direction or contrary to the useful'current. e V During normal operation the transformers 8 permit a'current to flow in the control conductor, this current'bearing a certain intensity or phase-displacement or both,

'upon which relation the differential relays are adjusted. .Now,' in case of leakage, the electric equilibrium of the current relationsin the four windings of the transformers 8 is disturbedand another distribution of currents takes place. These conditions are shown by way of". example by the arrows in Fig. 5, which indicate the direction of currents and inductions in a certain casewhen the disturbance by leak? age results in reversing the induction in the transformer 8 situated on the right of the drawing. Thereby the current in the control conductor is altered with respect to the main current, In case of a break down of the thin insulation between control conductor and main conductor at the defective spot as indicated-at l6the action of the control system is not essentially dififerent but rather enchanced each transformer 8 now working upon its own-circuit 12."16. Therefore in any case of leakage or defect the equilibrium of the differential relays 5 will. be interfered with and thereby the section switches actuated.

It is a further advantage of my invention that the conductors 1 and 2 and the relays or operating devices 5 being normally in closed circuit condition, the working order of the control'system is constantly visible. Furthermore a high degree of sensitiveness of the control system even running without load, is obtainable, and a vvery reliable opera tion of the entire net is attained on account 139 of the 'whole control system forming part of the main conductor itself and thus offering no additional weak points of insulation. Another form of this invention is shown by Fig. 6, which refers to the case when the nearly pure capacity charging currents flowing into the control conductor 2 are used for maintaining the normal equilibrium of the control system. This form of the system also offers a very high sensitiveness to incipient defects or leakage. By means of ohmic resistances 10 interpolated in the control circuit 2, by transformers of the same character as those indicated at 8 in Fig. .5, or byboth of these means together the useful current may be sufficiently or fully prevented from entering the control conductor thus leaving only a charging current inflow of well defined intensity into the control conductor at each section end, the control conductor being supposed to occupy part of the surface of the main conductor, for instance as shown by Figs. 1 and 2. It is preferable, within certain limits, to shape the control conductor so as to increase its surface and own ohmic resistance. These capacity currents therefore will be practically independent of the current load of the line section duringnorlnal working condition and determined only by voltage and capacity of the ection. Therefore they may be used to maintain a condition of equilibrium in appropriate relays for instance the control currents flowing into a. plurality of section ends of one phase at the same station of a line may operate a common difi'erential relay 15.

Relays of this kind (15) are to normally maintain the section switches 41; and 4 in their operative position but to actuate them in order to breakthe main circuit in case of disturbance. These relays otherwise may be of any recognized type,preferably of the electro-dynamometrical or induction type. A commencing defect in the control section 2 concerned causes current shocks and waves which, being mostly watt currents, alter the balanced position of the movable part of the relays 15 in one direction or other whereby the throwing open of the switch 4 or 4 on the faulty side of the relay is effected. The

right hand part of Fig. 6 indicates a branching point 13 with correspondingly adapted apparatus. As above 'mentioned' transformers 8 may replace or complete the function of the resistances 10 at this branching point also. V i

Fig. 7 is a diagram showing the use of my invention in connection with a distributing system having an ordinary switching off station without any current dlstributing branch controlled by the switch. In this case an ordinary stationary magnetic relay having transformer coils, which responds to a current of either direction will be suf ficient. The 'two coils 5 are oppositely wound on an iron core and balanced. In case of disturbances the magnetic equilibrium in the iron is affected and inductionis produced in the auxiliary coil 5 according to the difference in intensity and phasedisplacement between the two control currents and thus the switch 4 is actuated. The device for actuating the switch 4: when a current is induced in the coil 5, has not been shown in Figs. 7 and 8, devices of this character being well known in the art. The structural relation of the main conductor 1 to the control conductor 2 is not illustrated in these views, being of any suitable character, for instance as shown in any one of Figs. 1 to 4. The normal equilibrium of intensity and phase-displacement between said two currents may be regulated bymeans of transformers l1 acting upon a second secondary circuit with adjustable impedance.

Fig. 8, represents a modification of Fig. 7, employing the same relay whichby suitable devices of well known character (not shown) connected with the auxiliary coil 5' operates the two interlocked switches 4. The windings 5 again carry the control currents. The windings 5 together with the transformers 11, however, serve to neutralize the effect of the useful current driven into the control conductor by the drop of voltage. The feathered arrowsshow how this part of the magnetic field of the windings 5 is counter-balanced by the adjustable current of the windings 5.

Fig. 9 shows a modification of Fig. 5. While Fig. 5 amply allows the use of control conductors of-any described shape and position, the present modification prefers the use of a control conductor 2 situated in the interior of and thus electrostatically shielded by the main conductor 1. The transformers 8 are connected in series and opposite to and compensating the normal drop of voltage in the section, thus rendering the control conductor nearly perfectly free from current, useful current and capacity current as well.

Simple relays 5 are interpolated in the control conduit 2 to actuate by means of suitable devices .(not shown) the respective section switches 4: on both sides of the trans former station 7 in 'case of disturbance when the current compensation in the control circuit 2 is upset.

The modification according to Fig. 10, shows how to employ two or more control conductors 2 and 2- co-ordinated to and preferably in the interior of each main conductor. he secondary windings of the transformers 8 are preferably subdivided to form part of each control circuit. They are according'to the arrows, connected in such a manner as to act oppositely in their respective circuits at the same section end and opunder the electrostatic and magnetic influence of their main conductor may. 1normally carry their share of the current load, and mutually maintain the balance otdifferential relays 5 through which flow both of the control currents, In case of defect, however, the fixed relation between thecontrol currents in 2 and 2 is upset both by the changed electromagnetic induction and by a possible local destructionfof insulation whereby thesection switches on both sides of the damaged section are actuated through the medium of any devicesof well known or approved character (not shown) controlled bythe difierential relays 5.

Fig. 10, as an example of using a plurality of conductors, of course, may be modified in various ways,- i. e. the mutual intensit and direction of'the action of the transtormers 8 may be altered: in any way which will-enable me to establish'normally control conductor both operating under the same working pressure and the current pass-- ing through the control conductor being dependent upon the, condition of the main con- .ductor, safety means adapted to be actuated by the current in said control conductor upon a defect occurring with the main conductor, and transformers interpolated .between said main conductor andcontrol conductor. I 1

2. Control system for the constituent sections of an electric current distributing net, 7 each section comprising a main conductor, a

control conductor bothoperating underthe same working pressure and the current passing-through the control conductor being de pendent upon the condition of the main conmluctor, transformers and electromagnetic releasing devices interpolatedbetween said main and control conductors 'andadjusted to be inoperative during normal operation but tobeoperativeiupon a defect occurring with the main "conductor, and vswitches adapted to be actuated by said releasing devices. I q r V.

3. Control system for the constituent sections of an electric current distributing net, each section comprising a main conductor, a control conductor both operating under the same Working pressure and the current passingthrough the control conductor being dependent upon the condition of the main conductor; and safety means adapted to be actuated by said control conductor current upon a defect occurring with the main conductor, and tension-affecting elements including voltage changing devices adapted to induce additional tension by the main current into the control conductor.

4. Control systemfor the constituent sections of an elect'ic current distributing net,

each section comprising a main conductor a control conductor both operating under the same working pressure and the current passing through the control conductor being de-' pendent upon the condition ofthe main conductor. and safety means adapted to be actuated by said control conductor current upon a defect occurring in the main conductor tions of an electric currentdistributing net,

each section comprising a main conductor, a control conductor both operating under the same working pressure and the current pass ing through the control conductor being dependent upon the condition of the main conductor, andsafety means adapted to be actu ated by said control conductor current upon a defect occurring in the 7 main conductor and tension-afl'ecting elements interposed between said conductors, the "tension elements being oppositely connected to the normaldrop of voltage so that the control conductor is normally without current and single relays may be employed.

6. Control system for the constituent sections of an electric current distributing net each section comprising amain conductor, a control conductor both operating under the same working pressure and the current passing through the controlfconductor being dependent upon the condition of the main con ductonand safety means adapted to be actuated byjsaidv control current upon a defect occurring in the main conductor, said safety means including differential relays influencedby the main conduct-or current and by the. control conductor current. V i

7. Control system for the constituent sections of an electric current distributing net, each section comprising'a main conductoiya control conductor permanently connected with the main conductor at each end of the ing through the control conductor being dependent upon the condition of the main conwhich" flow the control conductor currents of two adjacent branches. 7

v8..Control system for the constituent sections of an electric current distributing net, each section comprising a main conductor, a control conductor both operating under the same working pressure and the current passing through the control con ductor being dependent upon the condition of the main conductor and safety means adapted to be actuated by said control conductor current upon a defect occurring in the main conductor, tension-affecting elements interposed between said conductors, said tension elements normally equalizing strength and phase of the currents of two adjacent sections and a differential relay related to both of said sections.

9. Control system for the constituent sections of an electric current distributing net, each section comprising a main conductor, a control conductor both operating under the same working pressure and the current passing through the control conductor being dependent upon the condition of the main conductor, and safety means adapted to be actuated by said control conductor current upon a defect occurring in the main conductor, and tension-affecting elements related to said conductors, said tension elements including current transformers for normally neutralizing the influence of the drop of tension upon the safety means.

10. Control system for the constituent sections of an electric current distributing net, each section comprising a main conductor and a plurality of control conductors, permanently connected with the main conductor at each end of the section, all of saidconductors operating under the same working pressure and the current passing through the control conductors being dependent upon the condition of the main conductor, transformers in circuit with said control conductors and circuit-breaking switches controlled by said transformers and maintained in their inoperative circuit closing position during normal operation, said transformers operating to normally neutralize the influence of the drop in tension upon said switches.

11. Control system for the constituent sections of an electric current distributing net, each section comprising a main conductor, a control conductor both operating under the same working pressure and the current passingthrough the control conductor being dependent upon the condition of the main conductor, and safety means adapted to be actuated by said control conductor current upon a defect occurring in the main con ductor, and tension affecting elements including ohmic resistances to promote the predominance of the capacity charging current in the control conductor.

' 12. In combination with a sectional main conductor, a. series of control conductors, each connected with the main conductor at both ends of the respective section, transformers included both in main and control conductors, to normally produce a condition of equilibrium, and circuit-controllers operated by a disturbance of such equilibrium.

13. In combination with a sectional main conductor comprising a core and a shell, a series 'of'control conductors each connected withthe main conductor at both ends of the respective section, transformers included in the core portion circuit of the main conductor and in the control conductors, to normally produce a condition of equilibrium, and circuit controllers operated by a disturbance f such equilibrium.

14:. In combination with a sectional main conductor, a series of control conductors having a resistance different from that of the main conductor, each control conductor being connected with the main conductor at both ends of the respective section, transformers included both in main and control conductors and having a transformer ratio differing from the ratio of the resistance of the main conductor to that of the control conductor, and circuit-controllers operated by a disturbance of the electrical condition normally prevailing in the control conductor.

15. In combination with a sectional main conductor, a series of control conductors having a resistance difi'erent from that of the main conductor, each control conductor being connected with the main conductor at both ends of the respective section, transformers included both in main and control conductors and so connected relatively to the normal drop of voltage in the main conductor that the control conductor will be normally without current, and circuit-com trollers operated by a disturbance of the electrical condition normally prevailing in the control conductor.

16. In combination with a sectional main conductor, a plurality of control conductors each connected with the same section of the main conductor at both ends thereof, section circuit controllers related to the main conductor sections, transformers in circuit with each of the control conductors con nected with the same section, and devices, under the electrical influence of said transformers for actuating said circuit-controllers, said transformers operating to normally neutralize the influence of the drop in tension on said devices.

17. In combination with a sectional main conductor, a series of control conductors each connected with the main conductor at both ends of the respective section, means for promoting the predominance of capacity currents in the control conductors, circuitcontrollers related to the main conductor sections, and devices, related operatively to said control conductors and adjusted to the adjacent sections, for actuating said circuit said capacity currents, for actuating; said controllers. I circuit-controllers. V In testimony whereof I have hereunto af- 18.111 combination with a sectional main fixed y Sig at e n t e presence of two 5' conductor, a series of control conductors Witnes es. V 7 each connected Wit 1-the main conductor ermanently at both ends of the respective secv M I 'HOGHSTADTER' tion, circuit-controllers related to the main Witnesses: conductor sections; and devices each related HENRY HASPER, 1,0 operatively to, the control conductors of tWo WOLDEMAR HAUPT. 

